A study of phenotypic variation ofStaphylococcus epidermidisusing Congo red agar

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Abstract
This study examines a series of phenotypic variants ofStaphylococcus epidermidisthat were generated from a pair of parent variants, isolated from valvular tissue of a patient with prosthetic valve endocarditis. The variants were initially classified by examining their colonial morphology on Congo red agar. In addition to differences in Congo red binding and colonial morphology, they differed in the expression of several surface components and enzymes. Despite these phenotypic differences, all variants had the same restriction endonuclease profile of plasmid DNA. Examination of a collection of clinical isolates demonstrated that phenotypic variation is a common property ofS. epidermidis. The ability to express different combinations of surface components and enzymes could contribute to the virulence ofS. epidermidisstrains by enabling these organisms to colonize a range of diverse environments.